This proposed multicenter, multinationial, randomized, double-masked controlled clinical trial has been designed to evaluate the efficacy of inhaled nitric oxide (INO) in the treatment of term and near-term infants with hypoxic respiratory failure. The trial will be conducted jointly by the Canadian Inhaled Nitric Oxide Study Group (CINOS) and the NICHD Neonatal Intensive Care Units Network. Infants are followed to death or discharge to home. Surviving infants will be assessed at 18-24 months corrected age. The proposed trial will compare INO therapy to a control group that receives either oxygen or no flow as a control and will otherwise incorporate conventional management strategies, specifically, treatment with surfactant and high frequency ventilation as adjuncts to INO therapy. It will also provide information about the response to high doses of NO (80 ppm) in infants who fail to respond to low doses of NO (20 ppm) with an increase in their PaO2 of >20 torr. A significant benefit is defined as a 40% relative reduction in the risk of death or of the initiation of ECMO. As part of the secondary research questions, the study will also compare the control and INO groups, focusing on: the change in PaO2 levels, mean OI and Aa-DO2 levels before and 30 minutes after initial administration of the study gas; neurodevelopmental outcomes as assessed at 18-24 months corrected age; the average length of hospitalization among surviving infants; the number of days of assisted ventilation; the incidence of air leak; the incidence of chronic lung disease; the proportion of infants transferred for potential ECMO and the associated costs. The GCRC will provide space and personnel to assist with the 18 to 24 month neurodevelopmental assessments. The nine sujects enrolled in the follow-up study will complete the assessments in early 1999. Data is in analysis.